1. Field of the Invention
The present invention relates to an IC socket and more particularly to an IC socket in which a shielded loop probe is built in the vicinity of a terminal or is capable of being inserted.
2. Description of the Related Art
It is known that most of the radiated emission generated from electronic apparatuses is caused by high frequency currents flowing from/into an IC (Integrated Circuit). Therefore, to control EMI (Electro Magnetic Interference), it is indispensable to take effective measures for designing after measuring a high frequency current flowing through the IC.
However, a current flowing through an existing high speed IC has a high frequency. Thus, under the existing conditions, it is very difficult for a conventional current probe, a conventional oscilloscope or the like to directly measure the current.
A technique is proposed in which a magnetic probe measures a magnetic field generated from an IC and then a time domain of the current is obtained on the basis of the measured magnetic field. (See, Pages 10 and 11, xe2x80x9cMeasurement of Magnetic Field near a PCB and its Application to EMC Problemsxe2x80x9d by SASAKI and HARADA, Technical Report of the Institute of Electronics, Information and Communication Engineers, December 1997).
Next, a description is given of a conventional technique with reference to FIG. 7.
A magnetic probe (shielded loop probe) 46 is produced by a multilayer printed circuit board production process or a semiconductor production process and is provided with three conductor faces (layers) and dielectric faces (layers) therebetween. In FIG. 7, conductor layers 41, 42, 43 are respectively insulated by dielectric layers, and thereby the magnetic probe is formed into like a coaxial cable. The conductor layers 41, 43 correspond to GNDs and the conductor layer 42 corresponds to a core wire of the coaxial cable.
As above described, the magnetic probe 46 is produced by a multi layer structure of a printed circuit board. The probe 46 is fixed in the vicinity of a wiring on an printed circuit board or a pin of an IC to be measured with a fixing jig, and then measures a magnetic field.
The loop is formed by the printed circuit board process or the like, therefore, it is possible to make a probe smaller and closer to an object to be measured than a loop probe using a semirigid cable. As a result, it is possible to obtain high resolution. (See, Page 18, FIG. 5 xe2x80x9cA Magnetic Probe with Multlayer Structure for High Spatial Resolutionxe2x80x9d by TAMAKI, MASUDA, and YAMAGUCHI, Technical Report of the Institute of Electronics, Information and Communication Engineers, July 1997).
Further, Japanese Laid-Open Utility Model Application No. Hei4-53562 discloses a probe measuring a magnetic field. The probe uses a coil and is built-in an IC socket.
Japanese Laid-Open Patent Application No. Hei8-271579 shows an IC socket capable of detecting an electric potential of a lead in an IC accurately. In this IC socket, the lead of the IC is electrically conductive with a probe via a contact. The probe is formed into a pole, since it is inserted into a hole of the IC socket so as to touch the contact.
Japanese Laid-Open Patent Application No. Sho62-177456 shows a probe in which a characteristic impedance is constant at any position of the probe. The probe is used in contact with a pad of an IC, an LSI or the like, and is formed into a pole so as to meet this usage.
However, there are problems in the above-described conventional techniques.
In a first problem, to reduce magnetic field effect generating from pins other than those to be measured for accurate measurement, it is necessary to make an interval between a pin to be measured and a shielded loop probe or an interval between a pin to be measured and a coil shorter than a pin interval of the IC. However, it is difficult to arrange the shielded loop probe and/or a coil in the vicinity of the pin to be measured.
As its causes, a cable and an IC socket are positioned in the vicinity of an IC to be measured, therefore, it is difficult to keep a position for the shielded loop probe. Further, when a coil is built in an IC socket, it is difficult to produce a coil smaller than a pin interval of an existing IC.
In a second problem, a pin interval of an IC is provided in units of mm, therefore, it is necessary to position a shielded loop probe with 0.1 mm accuracy for accurate measurement. However, it is difficult and troublesome to position the shielded loop probe in the vicinity of the pin to be measured.
As its causes, the shielded loop probe is separate from a measuring system, therefore, it is necessary to replace a magnetic probe by hand. As a result, the operation becomes troublesome, and the shielded loop probe is not in its position subtly.
In a third problem, concerning the IC socket shown in Japanese Laid-Open Patent Application No. Hei8-271579, the probe and the terminal are electrically conductive, therefore, it is impossible to measure the magnetic field caused by the high frequency current flowing through the IC terminal.
In view of the above, it is an object of the present invention to provide an IC socket capable of measuring a magnetic field generating from a pin of an IC accurately and easily.
According to a first aspect of the present invention, there is provided an IC socket having:
a terminal electrically connected with an IC, and a shielded loop probe built in vicinity of the terminal.
Also, according to a second aspect of the present invention, there is provided an IC socket having:
a terminal electrically connected with an IC, and a shielded loop probe capable of being inserted in vicinity of the terminal.
In the foregoing second aspect, a preferable mode is one that wherein further includes a slit through which the shielded loop probe is inserted.
Also, according to a third aspect of the present invention, there is provided an IC socket having:
a terminal electrically connected with an IC, insulation covering the terminal, and a shielded loop probe put on a surface Also, a preferable mode is one wherein a width of the shielded loop probe is approximately 0.3 through 1.0 mm. therefore, it becomes unnecessary to prepare the shielded loop probe by hand. As a result, measurement can be carried out easily and accurately.